diff --git a/QuickFIXn/Message/Message.cs b/QuickFIXn/Message/Message.cs
index f5c97a41b..0463896e8 100644
--- a/QuickFIXn/Message/Message.cs
+++ b/QuickFIXn/Message/Message.cs
@@ -495,6 +495,7 @@ protected int SetGroup(
                     {
                         // We were already building an entry, so the delimiter means it's done.
                         fieldMap.AddGroup(grp, false);
+                        grp = null; // prepare for new Group
                     }
 
                     // Create a new group!